I have dreamed of celebrating my 50th birthday in Italy by eating where the locals eat, making olive oil, making pasta, and staying a villa.
You can fulfil your dream, but as someone who has been in Rome in August and Tuscany in December, I heartily recommend you go during the off season.
We ate where the locals ate and were the only ones there not from the community. One restaurant owner joined us, at our invitation and we watched football (soccer) together while he gave us lessons in basic Italian, including how to scream at the TV!
Tuscany would be wonderful. You'll have to check your options if you plan on public transportation, especially if you want to stay at a villa. Driving is easy, so consider a rental car if you are comfortable driving. That will really expand your options to explore the countryside and the charming hill towns nearby.
When we were there in December, a few mornings were ~35F, but would heat up into the upper 50s or low 60s in the afternoon. In the 10 days we were there, it drizzled only once and that was the day we visited the Uffizzi. It is true the sun sets earlier, but twilight in Tuscany is a magical time.